$$ \begin{aligned}4x(x^2-3x+5)& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}4x^3-12x^2+20x\end{aligned} $$ | |
① | Multiply $ \color{blue}{4x} $ by $ \left( x^2-3x+5\right) $ $$ \color{blue}{4x} \cdot \left( x^2-3x+5\right) = 4x^3-12x^2+20x $$ |